(1) Field of the Invention
This invention relates to a process for isomerization and transalkylation of alkylphenols and for phenolderivatives in the presence of a catalyst comprising ironoxide (s) and at least one additional oxide and in the case of 2,4,6-trimethylphenol and 2,4-dimethylphenol as alkylphenol feed, of ironoxide (s) or of a catalyst comprising ironoxide (s) and at least one additional oxide.
(2) Description of the Prior Art
Isomerization and transalkylation of alkylphenols in the presence of acidic catalysts are known for a long time. GB-PS No. 695 464 discloses a process in which the use of aluminum silicate and of mixed oxides of silicon, beryllium, magnesium, aluminum, zirconium and titanium for isomerizations and transalkylations of alkylphenols is described.
In DE-OS No. 18 04 632 isomerizations and transalkylations are disclosed with mixed catalysts consisting of alumina and silicic acid.
The known processes however are not satisfactory with regard to technical scale operation, since the conversion to desirable products from an economical point of view, for example to monoalkylphenols, 2,6-resp. 2,4-dimethylphenol or 2,3,6-trimethylphenol is relatively low. This is also the case if alkylphenols comprising several alkyl groups, are converted in the presence of phenol.
Effective, technically useful catalysts, which permit the isomerization and transalkylation of alkylphenols with up to five alkyl groups and alkylphenols mixtures, which additionally contain residues originating from technical units, in the presence of relatively small amounts of added phenol in order to obtain useful products are not known. With the catalysts of the state of the art only negligible amounts of residues are converted to desirable products.